The effect of leakage on the acoustic performance of reactive silencers

The effect of leakage on the acoustic performance of reactive silencers, such as expansion chambers, Helmholtz resonators, and quarter-wave resonators, are analytically and experimentally investigated. The impact of the size and location of circular holes on the transmission loss of the silencers are explored in the absence of mean flow. One-dimensional analysis and perforation impedance theory are applied for the predictions of the transmission loss of the silencers with and without leakage. The experimental results are measured by an impedance tube setup and compared with the predictions. The results indicate that the one-dimensional analytical approach is effective for the prediction of acoustic behavior of the silencers considered in this study. For the expansion chamber, the impact of leakage is insignificant and limited to very low frequencies. The leakage at the cavity of the Helmholtz resonator shifts the resonance to higher frequencies with lower magnitude. Unlike the leakage at the chamber and cavity, the leakage at the lower part of the side branch hardly changes the acoustic behavior of the quarter-wave resonator.